Field of the Invention
This invention relates generally to the field of computer processors. More particularly, the invention relates to an apparatus and method for non-uniform frame buffer rasterization.
Description of the Related Art
Virtual reality (VR) is becoming an increasingly viable option for immersive applications, such as games and various industry applications. The reason for this is that companies, such as Oculus, Samsung, and Sony, have produced affordable head-mounted displays that are small and that have high image quality, low latency, and head tracking capabilities. It has been said that these head mounted displays will be the “last platform” in the sense that they will ultimately provide a fully immersive virtual reality experience which is indistinguishable from reality.
One problem, however, is that rendering needs to be done for both the left and right eyes of the user, which doubles the load on the graphics processor. In addition, the rectangular images are warped in order to compensate for the lenses inside the head-mounted display (HMD). This is illustrated in the example shown in FIG. 13.
Each warped image is typically generated from an intermediate image rendered using regular (“un-warped”) planar projection techniques. In the image in FIG. 14 illustrates how the final warped image would look on such a planar image. In this illustration, only 10×10 out of every 15×15 pixels are shown in order to better visualize the warp function shape and to make the intermediate rendered image more visible. The pixels are sparse towards the edges of the images, implying that many more pixels will be rendered in this intermediate image than will be used to create the final image. Consequently, significant redundant work is performed. The useful pixel density at the upper and lower edges of the intermediate image is 1/18, at the right edge it is 1/20, and in the right corners the pixel density is only 1/38, i.e., one useful pixel per 38 rendered pixels.